Solve for $x$ and $y$ using substitution. ${x+y = -3}$ ${y = -5x-11}$
Solution: Since $y$ has already been solved for, substitute $-5x-11$ for $y$ in the first equation. ${x + }{(-5x-11)}{= -3}$ Simplify and solve for $x$ $x-5x - 11 = -3$ $-4x-11 = -3$ $-4x-11{+11} = -3{+11}$ $-4x = 8$ $\dfrac{-4x}{{-4}} = \dfrac{8}{{-4}}$ ${x = -2}$ Now that you know ${x = -2}$ , plug it back into $\thinspace {y = -5x-11}\thinspace$ to find $y$ ${y = -5}{(-2)}{ - 11}$ $y = 10 - 11$ $y = -1$ You can also plug ${x = -2}$ into $\thinspace {x+y = -3}\thinspace$ and get the same answer for $y$ : ${(-2)}{ + y = -3}$ ${y = -1}$